Databases

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Databases
Dimitar Hristovski, Ph.D.E-mail
dimitar.hristovski_at_mf.uni-lj.si Institute of
Biomedical InformaticsMedical FacultyUniversity
of Ljubljana, Slovenia
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Motivation

• Technological foundation for numerous biomedical
  applications electronic medical record,
  healthcare information systems, ...
• Personal level data entry and maintenance
  (during academic education and later) master
  degrees, Ph.D., research projects...
• Useful elsewhere as well
• Banks
• Insurances
• Government institutions

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Computer Supported Data System

• Computer supported data system system for
  manipulation and processing of data, has four
  components
• Human user
• Program
• Data
• Computer

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Computer Supported Data System
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Data Revolution

• First period the computer is the major
  component.
• Second period software revolution, the programs
  (software) becomes the major component.
• Third period data revolution, data becomes the
  central component.

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Data as the Central Component
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Database - Definitions

• Database is a model of an organization, which is
  used as a basis for decision making and action
  planning.
• Database is a set of logically related data,
  stored in a computer system, the access to which
  is centralized and possible through a database
  management system (DBMS).
• Database is a mechanized, multi-user, formally
  defined and centrally maintained collection of
  data.

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Database Management

• Data is the foundation upon which the entire
  functioning of an organization is based.
  Therefore, just as any other important resource,
  data should be carefully managed, which includes
• Providing data availability
• Control of data usage

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Providing Data Availability

• Efficient access
• Of all users
• Concurrently
• To all types of data
• All the time (24 x 7 x 365)

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Control of Data Usage

• Data integrity
• Database backup and recovery
• Control of concurrent data access (transactions,
  commit, rollback)
• Data entry control and validation
• Using data according to their intended purpose
• Understanding the meaning of the data
• Access only to allowed data (based on type of
  user)

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Database Organization

• In a more general sense, the database consists
  of
• Data
• Users and user programs
• Database administrator
• Database management system (specialized piece of
  software)

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Types of Databases from Management Point of View

• Centralized database
• Distributed database

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Database Users

• Direct users
• Non-programmers (menu guided users, query
  language users, )
• Programmers (query language users, application
  programmers, system programmers, database
  administrator, )
• Indirect users

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The Data Part of a Database

• Physical database the values of the data
  elements
• Meta-database descriptions of the physical
  data
• How is the data stored in permanent memory?
• What is the meaning of the data?
• How is the data accessible to the users?

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Meta-Database

• Has three level architecture
• External schema
• User view model of organization as seen by a
  particular type of user (e.g. physician, nurse,
  accountant, )
• Conceptual schema
• Global organization model
• Internal schema
• Collection of logical records

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Data Independence

• Changes of one schema should not have influence
  on another schema.
• Physical data independence
• Logical data independence

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Data Models

• A particular schema is described using a
  structured description mechanism data model,
  also known as data description language.

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Data Model Types

• Surface
• Relational
• Network
• Hierarchical
• Object-relational
• Deep
• Entity-relationship
• ...

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Entity-Relationship Models

• Entity any concrete or abstract object or event
  in a organization or its environment, that we are
  modeling (the real world) (e.g. Patient, Test,
  Student, ...)
• Attribute a characteristic of an entity
  something we want to know about the entity (e.g.
  Entity Patient Attributes Name, Last Name,
  Sex, Date of birth, ...)
• Values attribute values (e.g. NameJanez,
  SexM, )
• Relationship meaningful relation between
  entities (e.g. Exam relationship between
  entities Student and Course)

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Student Administration Office Entity-Relation
Diagram
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Simplified Hospital Data Model
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Relational Table Example - Patients
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Patients Table Structure
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Table - Tests
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Table (Relationship) - Results
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Screen Form Patients and Results
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Query-by-Example (QBE)
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Equivalent SQL Statement
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SQL (Structured Query Language)

• Create create an object (table, view, index, )
• Update one or more records
• Insert one or more records
• Delete one or more records
• Select search for data the result is a table